Several people, including a police officer, have been injured in a shooting outside the Hart Senate Office Building on Capitol Hill.
Police were reportedly pursuing a female suspect, who was apprehended and shot dead.
The suspect is believed to have tried to break through White House security barricades, before driving off towards the Capitol. Once there, shots were fired as the driver attempted to flee.
Authorities have lifted the brief security lockdown that was initially in place after the incident.
US officials said the incident appeared to be isolated and terrorism was not suspected.
The Hart Senate Office Building is 2.4 kilometres from the Washington Navy Yard – where, less than three weeks ago, a lone gunman got into the building and killed 12 people.